1. Field of the Invention
The invention concerns a seal for a valve upper part, in particular for a water appliance or fixture.
A valve upper part of this type is particularly useful for water, but could in principle however also be used for other fluids. Accordingly, when mention is made of water in the following and in the claims, it is to be understood that this term is intended to include also other fluids, for which the valve upper part is useable.
A sealing device is used for example in plumbing fixtures, wherein by means of axial displacement of control disk relative to a fixed base disk, such that when the valve is in the closed condition the flow-through of water is prevented, and when the valve formed by these disks is in the partial or completely opened condition, allows a controlled flow or flow-through of water.
2. Description of the Related Art
In known valve upper parts, for example in the valve upper part known from U.S. Pat. No. 5,184,324, the base disk and control disk are comprised of ceramic, which has the advantage that this material is almost completely friction-resistant, so that at least this part of the valve upper part, which is particularly strongly subjected to wear, exhibits an almost unlimited life duration. In place of ceramic it is possible naturally also to use a series of other hard and wear-resistant materials. The base disk is fixed against rotation in the valve housing in known manner by suitable devices, while the control disk, seated freely rotatable upon the base disk, is connected fixed against rotatation with a spindle. The valve comprised of base disk and control disk is operated by the rotation movement of the spindle or, as the case may be, the therewith connected handle or the like.
The seal between the seat of the fixture body and the valve upper part occurs via a rubber ring, which is fixed in the headpiece of the valve upper part, and seals by compression against the base disk or, as the case may be, the seat of the fixture body.
As long as the valve upper part is not assembled in the instrument or fixture body, the friction resistance between the base disk and control disk has no great significance, since the valve is more or less easy to operate. Only after the incorporation or assembly of the valve upper part in the instrument or fixture body does the resistance during rotation of the control disk become significant as a result of axial pressing or compression. The operation forces or, as the case may be, torsional forces during opening and closing of the valve have a substantial influence upon the ease of operation of the instrument or fixture. On the one hand, the valve should be easy to manipulate, so that the valve can be opened and closed both with handles and well as with round hand grips, on the other hand, a certain amount of resistance should be present, in order to be able to select an exact water metering. In the case of a wall installation utilizing handles, a certain amount of resistance is in fact highly necessary, so that the valve cannot open by itself.
A predefined resistance or, as the case may be, axial force corresponding to the specific appliance or fixture is besides this of advantage for the reason that this resistance also has an influence upon the ceramic disks rubbing upon reach other and otherwise also upon the axial slide ring present in such a valve upper part, whereby the eventual wear is minimized. This contributes likewise to a lengthening of the lifespan and product reliability.
It is expected that instruments or fixtures or as the case may be valves of this type are designed to withstand 200,000 to 500,000 cycles, all the while maintaining approximately constant operation force and smooth, jerk-free movement. In the past it was attempted to influence of the movement forces by various shapes, hardness and material quality of the seal devices, in order on the one hand to guarantee the water-tightness and on the other hand to achieve the optimal torsional forces. It has however been found in practice that this is not necessary, or only in certain conditions. The seat of the fixture body as well also the valve upper part, which are comprised of multiple construction components, have tolerances, which collectively influence the axial compression occurring at the sealing device. If one selects a soft or, as the case may be, filigreed seal, then one has a low friction resistance in the radial plane, however there is the danger of the breech of the water-tightness of the valve. This danger occurs in particular in the case of very diverse water pressures. Particularly in the case of small pressures or compressions and already mentioned filigreed seals there exits the danger that as a result of the low self-compression a lack of water tightness may result. There are diverse seat shapes, such as for example the step seat, which exercise a negative influence upon the above mentioned seal combination. Besides this, there can be caused pressure surges or pulses when a soft seal only has limited resistance. If one selects a harder material for the seal device, one achieves on the one hand an optimal compression; however, as a result of possible summation of tolerances so much pressure could be exerted upon the hard disks, in particular ceramic disks, that the torsional forces drastically increase. A substantial reason therefore lies in the fact, that the axial compression via the seal ring is transmitted surface-wise directly upon the base disk and therewith also upon the control disk and the slide ring.
The present invention begins at this point. It concerns the provision of a sealing ring for a valve upper part of this type, which is so designed, that also in the case of unsuitable tolerances (largest dimensions/smallest dimensions) a sufficient axial compression can be achieved, in order to guarantee the sealing of the valve, and at the same time a comfortable torque friction is provided between the valve disks for operation or manipulation.
This task is inventively solved in a seal device for a valve upper part (18) comprised of a valve housing (20) and a spindle (22) rotatable therein, in particular for plumbing fixtures. The sealing device is comprised of a base disk (32) fixedly associated with the valve housing (20) and a control disk (34) which lies rubbing against the base disk and controlling the water flow through the valve upper part (18). The base disk (32) and control disk (34) are produced from ceramic or ceramic type material. A sealing surface of the base disk (32) facing away from the control disk is held urged against a sealing ring (36) of rubber or rubber like material. The sealing surface is formed by a ring shaped projecting edge part (38) on the base disk (32) or, as the case may be, on the sealing ring (36), and a groove (40) complementary to the edge part (38) defined in the sealing ring (36) or, as the case may be, a receiving groove (64) in the base disk (32).
If the valve upper part provided with this seal device is screwed into the fixture body, then the edge part of the base disk penetrates into the soft rubber or the like of the seal ring, whereupon the groove remaining in the rubber lies against the flanks of the edge part. When on the other hand the base disk of ceramic or the like is provided with such a groove, then the rubber ring is provided with the projecting elastic edge part, which during screwing in of the valve upper part to the fixture body is pressed sealingly into the groove.
The axial compression thus does not act surface-wise directly upon the ceramic disk surfaces lying against each other, but rather via the edge part, which projects ending in an edge, and via the flanks thereof. Even the most unsuitable tolerances can be equalized therewith. As a result of the triangular shape design of the edge part, a distribution of the axial compression transmission occurs. On the basis of the axial pressure transmission by means of the edge part, the seal integrity of the valve can be guaranteed at any time, without however any noticeable increase in the axial pressure and thus the friction forces to be overcome during operation of the valve. At the same time as a result of this rubber/ceramic connection a supplemental stabilization of the ceramic base disk can be achieved.
The friction forces between base disk and control disk can be adjusted by changing the depth of submerging of the edge part in the seal ring.
In a preferred embodiment a reinforcing ring embedded in the rubber ring makes it possible in simple manner to adjust the depth of penetration of the edge part of the opposite lying groove.